Alternating-current system.



L. C. MARBURG.

ALTERNATING CURRENT SYSTEM.

APPLICATION mu) JAN. 1. I910.

1,144,149. Patented June 22, 1915 IIIIIIII WW w zytrfimw 52W mww zUNITED STATES PATENT OFFICE.

LOUIS C. MABBUBG, OF MILWAUKEE, WISCONSIN: ASSIGNOR, BY MESNEASSIGNMENTS, TO ALLIS-CHALMEBS MANUFACTURING COMPANY, A CORPORATION OFDELAWARE.

ALTEBNATING-CUBRENT SYSTEM.

Specification of Letters Patent.

Patented June 22, 1915.

To all whom it may concern Be it known that I, Louis C. Manners, acitizen of the United States, residing at Mllwaukee, in the county ofMilwaukee and State of Wisconsin, have invented certain new and usefulImprovements in Alternating-Current Systems of which the following is afull, clear, and exact specification.

M invention relates to systems of electrical istribution.

In many electrical systems the load fiuctuates very ragedly between widelimits, the upper limit 0 n greatly exceeding the capaeity of thegenerator supplying the system. In systems of'this sort it has beenproposed to connect across the line a dynamoelectric power device whoserotating member has large inertia, which power device acts as motor tostore up kinetic energy when the load on the line is light and asgenerator driven by such stored energy when the load on the line isheavy.

It is the object of my present invention to obtain in a system of thissort, especially where the system is an alternating current one, anarrangement by which the storing and giving up of the kinetic energy maybe more readily and accurately controlled.

The resent invention, which is a modification 0 that'st forth and broadlclaimed in my co-pending application erial No. 536,878, of even dateherewith, consists, like that set forth in said co-pending ap lication,in an arrangement whereby the re ation between the synchronous speed ofthe dynamoelectric power device and thespeed at which the power deviceis actually rotating under the influence of the rotating mass in whichkinetic energy is stored is varied, referably under the control of theload on t e circuit. In the arrangement set forth in this presentapplication, as well as in those set forth in said co-pendingapplication, there is a dyna-' mo-electric power device-having arotating member of large inertia, and this dynamoelectric power devicehas two windings arranged, when respectively rendered efiective, to givethe power device two different maximum motor speeds. The speed at whichthe power device normally runs is between these two speeds, and one orthe other of the two windings is rendered efiective according as theload on the circuit is light or heavy. When the load is light, thewinding which gives the higher maximum motor speed is efiective and thepower device acts as a motor to store up kinetic energy in its massiverotating member. "Vhen the load is heavy, the windin which gives thelower maximum motor speed is effective and the stored energy is given upto drive the power device as a generator to cause it to supply ener tothe circuit. In the specific modifications described in said eo-pendingap lication, these two windings are rendered e ective and ineffective byconnecting and dis-connecting them from the circuit carrying thevariable load. In the present application the same result is obtainedwithout changing the con nections of these two windings, but by va ingbetween zero and maximum values t e currents in other windingsinductively associated with the first mentioned windings. Preferably thewhole operation is automatic.

The various novel features of my invention will be apparent from thedescription and drawings, and will be particularly pointed out in theclaims.

The single figure of the drawin shows diagrammatically one embodiment omy invention.

The generator 10 supplies the distribution circuit 11-12-48, on whichthere is a load which fluctuates quite rapidlywithin wide limits. Thislead may be of any character, but the invention is especially applicableto those cases where the variable load is a power load, consisting, forinstance, of one or more rolling'mill motors. The generator 10 is hereshown as a threehase generator, but my invention in its broa er aspectis not limited to alternating/ aucet systems. Across the circuit ll-- 13is connected a dynamo-electric wer device the rotating member of whichas large inertia, as b being connected to the fly-wheel 14. Thisdynamo-electric power device is arranged to act as a motor to store upenergy in the fly-wheel when the load on the circuit 11- 1213 is light,and as a generator driven by the energy stored in the flywheel to supplycurrent to the circuit 1112--l3 when the load on such circuit is heavy.The arrangement for controlling the consumption and production of ener yof the dynamo-electric power device and y-wheel is the essence of mypresent invention.

The dynamo-electric power device iilustrated consists of two separateinduction mtors 15 and 16 having different numbers of poles, say eightand ten respectively. These two motors are mechanically connectedtogether and to the fly-wheel 14, preferably by being mounted on thesame shaft with the fly-wheel. These motors, as shown, are of the Woundrotor type, and have their primary windings permanently connected acrossthe circuit 11-12-13. The secondary windings of these motors areconnected, through normally closed switches 17 and 18 respectively, toopposite ends of a threephase resistance 19, which is divided into twoparts, one for each motor, by a shortcircuiting bar 20. The position ofthe shortcircuiting bar 20 is automatically adjustable by means of thesolenoid 21, responsive, as through a current transformer 22, to thecurrent supplied to the circuit 111213 by the generator 10. The solenoidis preferably so designed that its core has comparatively largemovements upon small chan es in the supplied current. The switches 1 and18 are opened, by solenoids 23 and 24 respectively, when theshort-circuitin bar 20 has been moved to cut a predetermined amount ofthe resistance 19 into the secondary circuits of the motors 15 and 16respectively. the two solenoids 23 and 24 being controlled by aninsulated extension 20 on the shortcircuiting bar 20. I

e dynamo-electric power device may be started in any desired manner.When the load on the circuit 1112-13 is small; and the current suppliedby the generator does not exceed a predetermined value, theshort-circuiting bar 20 is at its right-hand limit of movement and theeight-pole motor 15 operates with practically no resistance in itssecondary circuit. The solenoid 24 is energized at this time and holdsthe switch 18 open, thus breaking the secondary circuit of the ten-polemotor 16 and thereby rendering its primary winding ineflective. Theeight-pole motor 15 operates as a motor to store up kinetic energy inthe fly-wheel 14, the speed of the motor '15 approaching synchromsm as alimit.

As the load on the circuit 11-12- 13 rises and the current supplied tosaid circuit b the generator 10 increases, the solenoid 1 moves the barto the left to insert the resistance 19 gradually in the secondarycircuit of the motor 15, thus causing said motor, because of itsincreased slip, to take less current from the line. As this movementof'the bar 20 to the left continues Q because of the rising currentsupplied to the line by the generator 10, the extension 20 leaves thecontact 24*, thus causing the de energization of the solenoid 24 toallow the closing of the switch 18. The secondsr 65 circuits of bothmotors are new energi and the eight-pole motor 15 acts as motor,assisted by the fly-wheel 14, to drive the ten-pole motor 16 as aninduction generator to supply current to the line. There is thus acirculation of energy from the line through the motor 15, the commonshaft of the motors 15 and 16, and the motor 16 to the line again. Thiscondition preferably does not continue for a great while, as upon thecontinuance of the movement of the bar 20 to the left the extension 20engages the contact 23 to cause the energization of the solenoid 23 andthe opening of the switch 17. This renders the primary Winding of theeight-pole motor 15 ineffective, the ten-pole motor 16 now being drivenabove synchronism by the energy stored in the flywheel 14 and supplyingcurrent to the circuit 11 12-13 at the frequency set by the generator10. If the current supplied by the generator 10 still increases, the bar20 is moved still farther to the left, thus cutting more of theresistance 19 out of the secondary circuit of the induction generator 16and thereby causing the latter to supply more power to the line.

When the load on the circuit 1112-13 falls, and the current supplied bythe genera ator 10 to said circuit decreases, the solenoid 21 becomesweaker and allows the short-circuiting bar 20 to be moved to the rightby its spring, thus first increasing the secondary resistance of theinduction generator 16 and thereby diminishing the rate at which saidinduction generator supplies energy to the line, then causing thedeiinergization of the solenoid 23 and the closing of the switch 17 sothat the continued movement of the bar 20 to the right both increasesthe resist-- ance in the secondary circuit of the induction generator 16and decreases the resistance III the secondary circuit of the inductionmotor 15, and then causing the energization of the solenoid 24 and theopening of the switch 18 so that the further continuance of the movementof the short-circuiting bar 20 to the right merely diminishes theresistance in the secondary circuit of the induction motor 15. Thelength of the contacts 23 and 24 may be made anything desired, so thatthe period during which the secondary resistances of the two motors areboth varied may be long or short as compared with the periods duringwhich only one of such secondary resistances is varied. During all ofthis movement of the bar 20 to the right the energy supplied to the lineby the dynamo-electric power device 15 and 16 in combination with thefly-wheel 14 is diminished, passing from a positive value to a negativevalue. The cycle above described is repeated, with more or lesscompleteness. as demanded by the fluctuations in the load on the circuit11-12-48.

One specific embodiment of my invention has been described, but theinvention is not limited to it. The large inertia needed may of coursebe inherent in the rotor of the dynamo-electric power device, or may beobtained by having a separate fly-wheel mechanically connected to suchrotor, as by being mounted on the same shaft therewith; both forms areincluded when such expressions as a dynamo-electric power device havinga rotating member of large inertia are used. Indeed, in some of itsaspects the invention is applicable to other than alternating currentsystems. \Vhen two exciting windings are used in the dynamo-electricpower device, it is only necessary that they produce different maximummotor speeds; that is, that the speeds at which the counterelectromotive force becomes equal to the impressed electromotive forceshall be different.

In the following claims I aim to cover all those modifications which donot depart from the spirit and scope of my invention.

What I claim as new is:

1. In combination, a generator, an electric circuit supplied thereby andcarrying a variable load. a dynamo-electric power device connectedacross said circuit and having a rotating member which has largeinertia, said dynamo-electric power device being provided with twowindings which determine different maximum motor speeds, said windingsbeing permanently connected to said circuit during the operation of saidpower device and means responsive to the current supplied by saidgenerator to said circuit for rendering effective the winding whichdetermines the higher maximum motor speed when the current supplied bythe generator is below a predetermined value, and for rendering th otherwinding efiective when the current supplied by said generator is above apredetermined value.

In combination, a generator, an electric circuit supplied thereb adynamo-electric power device connect across said circuit and providedwith two windings which determine difl'erent maximum motor speeds. therotating member of said power device having large inertia, and meansresponsive to electrical conditions in said circuit-for rendering eitherof said windings effective or ineffective while at all times maintainingboth of said windings connected to the circuit during the operation ofsaid power denos.

3. In combination, a generator, a circuit supplied thereby, adynamo-electric ower device connected across said circuit an comprisingtwo motors havin different maximum motor speeds, a fly-w eel connectedto said dynamo-electric power device, and means responsive to electricalconditions in said circuit for rendering either of said motors cflectiveor inell'ective while at all times maintaining both motors connected tothe circuit during the operation of said power device.

4. In combination, an alternating current generator, an alternatingcurrent circuit sup lied thereby and carrying a variable loa adynamo-electric power device connected across said circuit and havin ato tating member of large inertia an fluxproducing means capable ofdetermining different numbers of poles and permanently connected to saidcircuit during the operation of said power device, an means responsiveto the current supplied by said nerator to said circuit for vaic-iyingthe 0 octive number of poles of sai dynamo-else tric power device in thesame sense as the current supplied by said generator varies.

5. In combination, an alternating current generator, an alternatingcurrent circuit supplied thereby and carrying a variable load, adynamo-electric power device of the induction motor type connectedacross said circuit during the operation of said power device, and meansresponsive to the current supplied by said generator for varying theeffective number of poles of said dynamoelectric power device and forvarying the secondary resistance of said power device.

6. In combination, an alternating current generator, an alternatingcurrent circuit supplied thereby and carrying a variable load,adynamo-electric power evice of the induction motor type having aplurality of primary windings ca able of determining different numbers0? oles, the rotating member of said power evice having large inertiaand all of said primary windings being permanently connected to saidcircuit during the operation of said power device, and means responsiveto electrical conditions in said circuit for rendering any of saidwindings effective or ineffective.

7. In combination, an alternating current generator, an alternatingcurrent circuit supplied thereby and carrying a variable load. twoinduction motors the primary windings of which are connected across saidcircuit during the operation of either of said motors, said two motorshaving different numbers of poles, a fly-wheel, said fly-wheel and saidtwo motors being all mechanically connected, and automatic meansresponsive to the current supplied by said enerator for opening andclosing the secon ary circuits of said motors.

8. In combination, an alternating current generator, an alternatingcurrent circuit sup lied thereby and carrying a variable load twoinduction motors the primary windings of which are permanently connectedacross said circuit during the operation of either of said motors, saidtwo motors havin difl'erent numbers of poles, a fly-wheel, saidfly-wheel and said two motors being all mechanically connected, andautomatic means responsive to the current supplied by said generator forvarying the resistance of the secondary circuits of said two motors.

9. In combination, an alternating current generator, an alternatingcurrent circuit supplied thereby and carrying a variable load, twoinduction motors the primary windings of which are permanently connectedacross said circuit, said two motors having different numbers of poles,a fly-wheel, said fly-wheel and said two motors being all mechanicallyconnected, resistance for the secondary circuits of said motors, andautomatic means controlled by the current supplied by said generator foropening the secondary circuit of the motor having the higher number ofpoles when such current is below a predetermined value and for open ingthe secondary circuit of the other motor when value and for varying theresistance in the secondary circuits of said two motors.

10. In combination, an alternating current generator, an alternatingcurrent circuit supplied thereby and carr ing a variable load, twoinduction motors t e primary windings of which are ermanently connectedacross said circuit, a 5 -wheel to which both of said motors aremechanically connected, the two motors tending when operating at theirres ective synchronous speeds to drive said y-wheel at different speeds,and automatic means controlled by the current supplied by said generatorfor controlling the secondary circuits of said two motors.

11. In combination, an alternating current enerator, an alternatingcurrent circuit supp ied thereby, two induction motors the primarywindings of which are connected across said circuit, said two motorshaving different numbers of poles, a fiywheel, said fly-wheel and saidtwo motors being mechanically connected, a variable resistance con--nected in common in the secondary circuit of each of said motors, andmeans responsive to the current in the supply circuit for such currentis above a predetermined the resistance of the secondary circuit 0 onemotor and decreasing the resistance of the secondary circuit of theother motor as the load increases.

12. In combination, a enerator, an electric circuit supplied there y, adynamo-electric power device connected across said circuit and providedwith two primary windlngs which determine different maximum motorspeeds, the rotating member of said power device having great inertia, asecondary circuit corresponding to each primary winding, a resistanceconnected in the circuit of each secondary, and means responsive to thecurrent in said supply circuit or consecutively increasing theresistance of the increasing a secondary winding corresponding to theprimary winding WlllCll gives the higher speed, completing the circuitof the secondary winding corresponding to the primary winding whichgives the lower speed, breaking the circuit of the first secondarywinding, and decreasing the resistance of the second secondary circuitas the load on said supply circuit increases.

13. In combination, a generator, an electric circuit supplied thereby, adynamo-electric power device connected across said circuit and providedwith windings which determine different maximum motor speeds, therotating member of said power device having great inertia, windingsadapted to coiiperate with said first windings in the operation of saiddynamo-electric power device, a common variable resistance adapted to beincluded in the circuit of said second mentioned windings. and meansresponsive to the electrical conditions in said circuit for varying saidresistance as the load on said circuit varies.

Milwaukee, iVis, Dec. 22, 1909.

In testimony whereof I afh'x my signature, in the presence of twowitnesses.

LOUIS (J. MARBURG. \Vitnesses ALEX J. Nicirr, Jr., CHAS. L. BYRON.

